In this photo released by Britain's Ministry of Defense, a member of the F Company (Fire Support) 1 Royal Welsh takes a retina image of an Afghan during operation "Moshtarak" Saturday, Feb. 13, 2010, near Marjah, in Afghanistan's Helmand province. British troops are among the thousands of NATO and Afghan soldiers who stormed the Taliban stronghold of Marjah by air and ground Saturday. (AP Photo/Ministry of Defense, SSGT Mark Jones)

A handheld retinal scanner the size of a camera. Crazy, this world we live in.

Don't quote me on this, but I believe the "i" is added to plural when the word ends in -us, not -is. Like cactus becomes cacti, octopus becomes octopi. However, the correct plural for iris, at least according to wikipedia, is irides.